An electrophysiologic examination will be made of the subcellular mechanisms underlying transmitter release from motor nerve terminals. The procedure will employ binomial statistics for estimating m (quantal content), n (available store) and p (probability of release). The effect of physiologic and pharmacologic alterations will be tested, in the hope of clarifying nature of n and p. This will include pH, temperature, osmotic pressure and stimulus frequency. Drugs will include catecholamines, curare, cholinomimetics, and extracellular markers, such as horseradish peroxidase, ferritin or globular proteins. BIBLIOGRAPHIC REFERENCES: Miyamoto, M.D. (1976) Electrophysiologic examination of the synaptic vesicle re-cycling hypothesis. New England Pharmacology Society Meeting. Univ. Conn. Health Center. Miyamoto, M.D. (1977) Estimates of non-linear summation at the frog motor end-plate. Fed. Proc. 36:977.